The present invention relates generally to an improved interface for use in connecting an external unit to an input/output (I/O) port of a personal computer (PC), and more particularly to a computer interface adapted to be plugged into a serial port of a PC, and which has the ability to transmit binary coded rf signals based on digital commands received from the PC.
There exist numerous applications in which an external unit is connected to the input/output (e.g. serial) port of a PC to receive and input binary or digital data to and from the PC. One such application is in an automated appliance control system such as the one disclosed in co-pending application Ser. No. 09/364,714,) the contents of which are incorporated herein by reference. In that system, a control interface unit receives digital commands from a PC over a RS-232 connector. The control interface unit, in response, produces rf binary data burst address and function control signals, which are applied to an ac power line for transmission to a plurality of control modules. An electrical appliance, lamp, or any other electrically operated device, is connected to one of the modules and is turned on or off in response to the function control signal received at its associated control module. Alternatively, the control unit may transmit those address and function control signals over the air to an rf transceiver, which retransmits and applies those signals onto the a.c. power line.
The programming of an appliance control system of this type, is, however, only one of the numerous potential applications of a PC. Other typical uses of a PC include the operation of a printer or a scanner, to which a connection from the PC is typically made at a serial or parallel input/output port of the PC. The number of such ports on a PC is, however, limited. The typical home PC includes only two or three I/O ports, so that choices must often be made regarding the use of the available input/output ports. Stated differently, if all of the PC I/O ports are in use at a given time, and the user wishes to commence an additional device to the PC, the user must disconnect one of the already connected output devices from its port, so that that port may be used to connect another output device, such as the appliance control unit referred to above. Thus, any time the PC is connected to any particular external device the number of available I/O ports in that PC is reduced by one.
It is an object of the present invention to provide an interface for I/O use with a PC which allows a greater number of output devices to be connected to the limited number of I/O ports in the PC.
It is a further object of the invention to provide a computer interface which is adapted to be connected to a PC I/O port to receive digital signals, and which converts this signal to corresponding rf data signals.
To this end, the computer interface of the invention includes a standard male connector and a female connector of the type that is typically inserted or plugged into the serial port of a PC. The male connector of the interface allows the PC serial I/O port to be also converted to an external device, such as a printer, which would normally be plugged directly into that serial port. An rf pulse modulator receives its operating power from the PC serial port and binary signals from the PC and modulates those signals onto an rf carrier.
The computer interface of the invention reformats and transmits binary data or commands from the PC. It also passes binary signals from the PC to an external device that is plugged into the other connector of the interface so that the interface is transparent to that external device. The serial I/O port of the PC, in which the interface of the invention is plugged, can thus be used to supply data to or receive data from another device, so that use of that port with the interface is not lost. The interface can be used to transmit binary coded r.f. address and function control signals derived from software running in the PC over-the-air to a transceiver located at a remote appliance control module.
An additional aspect of the PC rf interface of the invention resides in its use with a multi-unit remote control, which is an improvement over the remote control unit disclosed in U.S. Pat. No. 4,809,359. In the present invention, the binary coded rf control and address signals transmitted by the rf PC interface are received and demodulated to derive a sequence of binary coded remote control and address signals. Those signals are processed to further code them in accordance with the brand, e.g. Sony or Zenith, of audiovisual product, e.g. television or VCR, that is to be remotely controlled by the coded control signals.
To this end, a memory for IR code library that contains the universal remote control codes for all commercial brands of audio visual products, and a look up table that stores the remote control codes for all audio visual products in the user""s home are connected to a processor, in which the product codes are combined with the received binary coded control signals. The thus processed and modified binary coded address and control signal s are applied to an IR transmitting device, e.g. an LED, which transmits correspondingly coded IR control and address signals adapted to operate only with the selected, i.e. addressed, audiovisual product.